1. Field of the Invention
The present invention relates to a lithium secondary battery, and more specifically, to a lithium secondary battery having excellent low-temperature properties.
2. Discussion of Related Art
With the rapid development of the electronics, communications and computer industries, portable electronics and communication devices such as camcorders, mobile phones, notebook PCs or the like have remarkably developed. Accordingly, there is an increasing demand for a lithium secondary battery as a power source which may drive the devices. Particularly, research and development on the lithium secondary battery as an environmentally friendly power source in the field of applications of electric automobiles, uninterruptible power supplies, machine tools, artificial satellites or the like have been actively conducted in Korea, Japan, Europe and the U.S.A.
In secondary batteries which are being recently applied, a lithium secondary battery developed in the early 1990s includes: an anode such as a carbon material or the like which may intercalate or deintercalate lithium ions; a cathode formed of a lithium-containing oxide or the like; and a non-aqueous electrolyte solution prepared by dissolving a suitable amount of a lithium salt in a mixed organic solvent.
As the application range of the lithium secondary battery is expanded, the lithium secondary battery is used as a power source of electric automobiles or the like, and in such a case, performance allowing automobiles to be operated in a harsh environment such as higher temperatures or lower temperatures than that in mobile phones, notebook PCs or the like is required. Since automobiles should be operated at a low temperature such as in winter, excellent charge/discharge performance and output properties at a low temperature are typically required.
However, a low temperature environment results in severe problems of reduced charge/discharge performance and output properties due to a decrease in an electrochemical reaction rate, and thus there is a need of the development of a technique for a lithium secondary battery having excellent low-temperature properties.
Korean Laid-open Patent Publication No. 2014-118517 discloses a non-aqueous electrolyte solution additive for a lithium secondary battery.